The objective of this research is the definition of a relationship of bile acids or their derivatives to the etiology of cancer of the large bowel. Specifically, we propose to ascertain a) dietary effects on the nature and amounts of bile acids found in hepatobiliary circulation; b) the effect of gonadal and progestational hormones on the composition of biliary acids in animals; c) the effects of bile acids and their derivatives in the lumen of the colon on anabolic activities of epithelial cells of the colon. Gas liquid chromatography, thin layer chromatography, radioassay, and mass spectrometry will be used to identify and quantitate the acidic biliary constituents and fecal sterol and bile acids. Anabolic activity of the epithelial cells will be assessed by measurement of biosynthesis of proteins and nucleic acids.